Identification and Diagnosis

General Principles, Symptoms, and Subtypes

The process of identifying delirium is usually through longitudinal rather than cross-sectional assessment. This is because of the fluctuating nature of this mental disorder, and so it is important to assess mental state through at least a 24 hour period including changes from day to night. Another hallmark is an acute change in mental state progressing over hours to days, and often this will be accompanied by behavioural and functional changes. One of the standard ways to diagnose delirium is by using the Diagnostic and Statistical Manual’s (IV-TR) criteria (6), as outlined in Table 1, which focus on disturbances in consciousness and attention. Along with these symptoms, most will have sleep-wake disturbances, and sometimes there is a complete reversal in the cycle. While the “agitated” (hyperactive subtype) delirium tends to be identified sooner, it is worth remembering that some delirious persons can present in an “apathetic” (hypoactive subtype) state, which may not be deemed as problematic by caregivers and mistaken for depression (Lipowski, 1992). This can lead to poorer outcomes as compared to the “agitated” delirious person (Liptzin, 1992; O’Keefe 1999). An individual will most commonly fluctuate between the agitated and apathetic states. The cross-sectional exam may, but not always, demonstrate changes in attention or consciousness through the course of an interview, and may uncover psychotic thinking or misperceptions. A delirious person will most commonly have delusions which are of a persecutory nature, or illusions/hallucinations of a visual nature (APA DSM IV-TR). More subtle symptoms in the elderly (APA Practice Guideline 1999, Jacobson 1997, Levkoff 1996) can include:

  1. new-onset incontinence
  2. falling or refusal to mobilize
  3. dysarthria (slurred speech), dysnomia (difficulties naming), dysgraphia (difficulties writing)
  4. mild disorientation and difficulty judging the passage of time
  5. hypersensitivity to light or noise
  6. difficulty concentrating or changes in the speed of thinking
  7. emotional changes: irritability, euphoria, dysphoria, anxiety, hyper-vigilance, fear, lability in mood, apathy
  8. nightmares or vivid dreams

Pulling out I.V.’s and catheter lines may be adverse consequences. On occasion, once the delirium has cleared, the person may be left with persistent anxiety or even post-traumatic stress disorder (Jacobson 1997).

Underlying Medical and Psychiatric Causes: Precipitating and Perpetuating Factors

In general, delirium usually arises in the elderly due to multifactorial medical causes, and correctly identifying and treating them is important in managing delirium. There are a number of risk factors, as detailed later, which make a senior more prone to develop this syndrome. It is useful to divide up risk factors as predisposing, precipitating, and perpetuating.

For instance, a number of factors can be introduced in a hospital environment which may precipitate or perpetuate delirium, such as intravenous lines, catheterization or other instrumentation, sensory deprivation or overload, pain, immobilization, use of restraints, and inability to maintain bowel or bladder function (Inouye 2000). Incidence of delirium developing once hospitalized is between 5-30% (Cole 2004). Table 2 outlines some common causes, including certain medications, infection, dehydration, electrolyte disturbances, cardiac events, substance intoxication or withdrawal states, elimination problems, and stroke. The DIMS-R mnemonic is included. There is controversy whether environmental changes, such as relocation to hospital or intensive care setttings, can itself induce delirium in those who are susceptible, demented individuals (APA Practice Guideline 1999). Underlying psychiatric conditions may also lead to delirium. Depression or dementia can result in physical decline and susceptibility to acute medical conditions, while those with dementia are more likely to develop delirium than those without dementia (O’Keefe 1997a).

Medications Which Induce Delirium

Given the hypothesis that deficiency in the neurotransmitter acetylcholine is believed to be one of the central mechanisms in developing delirium, medications with anticholinergic properties will predispose to, or provoke, delirium. Common examples include the anti-nauseants, antihistamines, oxybutynin (Ditropan), and certain psychiatric medications (Moore 1999; Ham 2001). A number of commonly prescribed medications like narcotics, corticosteroids, cimetidine (Tagamet), warfarin have unrecognized but significant anticholinergic properties (Tune 2001) and therefore contribute to the overall anticholinergic load. Meperidine (Demerol) and morphine are narcotics particularly prone to precipitating delirium, and using hydromorphone (Dilaudid) or oxycodone (Oxycontin) may be better choices for the elderly. Table 3 gives some examples of medications linked to provoking delirium, including benzodiazepines (Marcantonio 1994, Gaudreau 2005).

Predisposing Conditions and Prevention of Delirium

Elderly persons are vulnerable to development of a delirious state when they have (Inouye 1993, Trzepacz 1996, Irving 2006):

  1. Dementia
  2. Advanced age older than 80
  3. Severe acute illness, multiple comorbid conditions, higher physical disabilities
  4. Sensory impairment (vision, hearing)
  5. Alcohol abuse
  6. Immobility
  7. Dehydration or low sodium levels
  8. Low serum albumin, often indicative of malnutrition
  9. Previous episodes of delirium
  10. Pre-existing medical conditions such as Parkinson’s Disease, liver failure
  11. Sleep deprivation

Careful history taking is essential in obtaining collateral information from family or caregivers about previous cognitive status, functional ability, medication use, and alcohol or sedative-hypnotic use. Asking about previous bouts of delirium caused by a medication (eg: specific narcotic) can prevent delirium from re-occurring.

In a multi-component, non-pharmacologic intervention for medically ill seniors which addressed some of these factors, the incidence of delirium was 9.9% compared to the 15% incidence in the usual care units (Inouye 1999), so it can be worthwhile modifying predisposing factors. Pharmacologic prophylaxis is not generally recommended at this time for those at high risk in developing delirium, though one study using low dose Haloperidol in a pre-operative fractured hip elderly population showed reduction in severity and duration of post-operative delirium. However, the incidence was not decreased compared to the placebo group (Kalisvaart 2005).

Differentiating the D’s (Delirium, Dementia, Depression)

Table 4 provides a summary of differences between these three mental disorders on various clinical domains. As demented individuals are more prone to be delirious, and a variety of symptoms can overlap between the two conditions, it is important to keep in mind that delirium is marked by an acute change with fluctuations over a 24 hour period while dementia generally does not. It can be very helpful in getting collateral information from family or other caregivers in regards to what has changed and how quickly. The term “sundowning” refers to a worsening in cognitive and/or behavioural disturbance towards night time, which can occur in either conditions but dementia (except Lewy Body Dementia) does not usually lead to fluctuations in consciousness and attention (Cole 2004). Some bedside tests to demonstrate attention span problems and distractibility may be useful in differentiating between them, such as digit span tests (O’Keefe 1997b) or counting days of the week or months backwards (Rudolph 2003). Depression can look like delirium because there may be psychomotor excitement or retardation, and there may also be cognitive problems related to diminished concentration and ability to retain information (one of the causes of “pseudodementia”). However, one should be able to differentiate depression from delirium readily in most cases. Hypoactive delirium can look similar to apathy in depression. As there can be generalized slowing on the electroencephalogram (EEG) in delirium (Jacobson 1997), this tool can help differentiate from these three conditions in select cases.

Additional psychiatric conditions such as severe mania and catatonia may mimic symptoms of delirium, but these are rarely seen.

Screening Tools

Useful screening tools for delirium incorporate longitudinal assessments, and both mental and behavioural symptom observations. It should be relatively brief and easy to use by front-line professionals. Cross-sectional cognitive measures such as the commonly used Folstein Mini-Mental Status Exam (MMSE) are not particularly useful in identifying or tracking the severity of delirium, and have low specificity. There are some tools that are useful in specific conditions such as alcohol withdrawal and delirium tremens, such as the CIWA-Ar in Table 5 (Sullivan, 1989), and more complex tools which quantify the severity of delirium (Trzepacz, 1994).

A very useful validated screening tool that can assist health care professionals with the identification of this complex phenomenon is the Confusion Assessment Method (CAM), short form version.

The CAM (Table 6) is a four-item screening tool used to identify the cognitive changes brought about by delirium (Inouye 1990). The criteria for assessment include onset and fluctuations, attention, ability to think and level of consciousness. The diagnosis of delirium requires the presence of Features 1 and 2, plus either Feature 3 or 4 (Henry 2002). This diagnostic algorithm takes about five minutes to administer and requires clinical judgment. The CAM has better sensitivity and specificity for delirium than other commonly used cognitive screening tools (Jacobsen 1997; Milisen 1998). Other brief nursing tools for detecting delirium have been reviewed elsewhere (Irving 2006).

Table 7 provides an algorithm of screening for delirium using the CAM, particularly in light of predisposing factors and the PRISME factors (see below).

Behavioural Assessment of Delirium

Nurses and other health care professionals often detect a behavioural change as the first indicator of delirium. It is essential that clinicians accurately describe the delirious person’s behavior (Neelon 1992; Rapp 2001). Nondescript words such as “confused” or pejorative terms such as “space cadet” fail to accurately describe a symptom of delirium and fail to recognize the delirious person’s emotional responses to illness. Agitation and aggression are often seen as behavioural symptoms, reflecting the delirious person’s distress, fear, frustration and anxiety. Cohen-Mansfield and Bilig (1986) classify three types of agitated behaviour:

  1. Aggressive behaviour (eg, hitting, kicking, spitting, resisting care)
  2. Physical non-aggressive behaviour (eg, restlessness, pacing, disrobing)
  3. Verbal agitated behaviour (eg, complaining, cursing, screaming, yelling)

Thus, non-purposeful and repetitive movements such as removing lines and tubes or picking at sheets and clothing are examples of agitation of the physical non-aggressive type. It is helpful to remember the following principles of behavioural assessment:

  1. Any sudden change in behaviour usually has a reversible cause
  2. All behaviour is meaningful to the delirious person
  3. Behavioural change may be a response to fear, anxiety, pain, or discomfort

In order to provide delirious person-centered interventions, it is important to identify and assess the problematic behaviour by asking the following questions:

  1. What type of behaviour occurs?
  2. When does the behaviour occur? What time of day?
  3. What happens before the behaviour occurs? After the behaviour?
  4. Who is impacted by the behaviour?
  5. What is the delirious person’s baseline behaviour?
  6. How stressful and/or threatening is the delirious person’s hospital environment?

Behaviour can be tracked in a log format for several days until a pattern emerges. Sleep patterns should be tracked at the same time as day-night reversal reflects neurobiological changes and is considered an important manifestation of delirium. Once patterns are better understood, the clinician can tailor the interventions to meet the delirious person’s needs.


PRISME is an acronym that can assist the clinician in identifying and relieving all the underlying factors that contribute to the onset and perpetuation of delirium. The factors are:

  1. P - PAIN


Pain is well known to be a factor in the onset of delirium (McCaffery & Pasero, 1999). Both acute and chronic pain should be fully treated with medications with low potential for cognitive side-effects.


Mechanical restraint devices are often used to control disruptive behaviour, prevent falls and maintain treatment devices (Frengley & Mion, 1998; Mion, Minnick, & Palmer, 1996). However, there is no evidence that demonstrates the effectiveness of physical restraints in protecting delirious persons and preventing injury. However, agitation and aggression may increase in response to restraint (Sullivan-Marx, 1994; Strumpf & Evans, 1988). Studies show that restraints can lead to more injuries, increased length of stay, increase the risk for developing delirium by 4.4 times in hospital (Inouye 1996), and lead to cognitive or functional decline (Fletcher, 1996; Swauger & Tomlin, 2000). Many physical complications arise from the use of restraints: reduced function, contractures, muscle atrophy, loss of bone mass, constipation, incontinence, dehydration, pressure ulcers, and even death. (Palmer, Abrams, Carter & Schluter, 1999) Psychosocial issues associated with restraint use include disorganized behaviour, depression, agitation, fear, humiliation, and demoralization. When restraints are removed, quality of life and functional status improve while the risk for hospital-acquired infections decline (Palmer, Abrams, Carter & Schlutter, 1999) and the potential for institutionalization is lessened.

In hospital settings, acutely ill persons who are agitated, aggressive, and pull at their tubes or lines are at high risk to be restrained. Because of the risks, restraints are not generally recommended (APA Practice Guidelines 1999). Health care for older adults emphasizes maximizing functional ability, promoting and restoring health, preventing and minimizing the disabilities of acute and chronic illness, and maintaining dignity and comfort until death. These goals are incompatible with the use of restraints. Instead, the nurse should carefully assess the delirious person’s physical, cognitive, and psychological needs using a format such as PRISME. Alternatives to restraint include environmental modifications, physiologic approaches, activity or other diversion techniques, and psychosocial interventions. The least restrictive means of restraint should be used if absolutely needed, and should be discontinued as soon as feasible.

As stated in the National Guidelines in the Assessment and Treatment of Delirium (CCSMH 2006), “physical restraints for geriatric patients suffering from delirium should be applied only in exceptional circumstances when:

  1. There is a serious risk for bodily harm to self or others OR
  2. Other means for controlling behaviours leading to harm have been explored first, including pharmacologic treatments, but were ineffective AND
  3. The potential benefits outweigh the potential risks of restraints.”


Bladder: Urinary tract infections (UTI) are a frequent source of delirium. In addition, delirious persons can be in urinary retention. Post-void residual bladder scanning can be helpful in identifying this. In and out catheterization should be done if necessary to ensure the bladder is decompressed and to obtain a urine specimen for culture and sensitivity. Urinary catheters should not generally be left in the bladder as they contribute to falls and further UTI’s. In addition, delirious persons may self-remove the tube and cause urethral damage.

Bowel: Delirious persons with an acute illness may be dehydrated, inactive and eating poorly. As a result, constipation is a common issue. The oral route is preferred for bowel management. However, the delirious person may need a rectal exam to determine if stool is occluding the urethra. In these situations, an enema may be required.


Infections such as pneumonia and UTI are a common cause of delirium. Delirious persons with a history of infection should be reassessed whenever their behaviour changes to suggest delirium. The clinician should collaborate with the physician to ensure appropriate blood tests are done and antibiotic treatment is commenced.

Sensory Impairment

Ensure the delirious person wears hearing aids and glasses and that the devices are clean and in working order. Perceptual disorders in delirium and magnified when the delirious person is unable to understand and respond to environmental stimuli.

Tip: For the hard of hearing, insert the earpieces of a stethoscope into the delirious person’s ears and talk slowly and, at first, quietly through the bell.


One of the first goals of care is to ensure the delirious person sleeps at night and is awake as much as possible during the day. Once day-night biorhythm is re-established, the delirium will begin to clear. Whenever possible, postpone routine care, such as taking vital signs and turning, during the night. Ensure the delirious person has short rest periods during the day. Making the delirious person stay awake all day will not necessarily promote sleep at night. Instead, the delirious person may become more agitated and aggressive due to fatigue and stress intolerance.


Delirious persons who take three or more medications are at higher risk of developing delirium (Inouye, 2000; Milisen et. al., 1998). The clinician should collaborate with the physician and pharmacist to carefully evaluate the indications, dosage and the desired outcomes for each medication.


Carefully evaluate metabolic parameters of the delirious delirious person. Hydration should be also be carefully monitored. Unless contraindicated, ensure the delirious person receives 1.5-2.0L of fluid daily (RNAO 2002).


Delirious persons with hyperactive delirium require less stimulation while those with hypoactive delirium require more. Adjust environmental, light, and numbers of people to the level that is comfortably tolerated by the delirious person. A nightlight in a dark room can relieve nocturnal anxiety. A calendar is helpful, and frequent re-orientation by staff or family can be beneficial. If the delirious person is hallucinating, or experiencing delusions regarding the purpose of equipment or the nurse, limit the exposure to medical equipment and tests and provide a continuous caregiver.


Delirious persons are often anxious and fearful, particularly if threatening delusions or hallucinations are present. Reassure the delirious person frequently. Encourage the family to stay with the delirious person whenever possible.